Radar-augmented sub-target

ABSTRACT

A remote controlled drone aircraft carrying radar-augmented targets or so-called &#39;&#39;&#39;&#39;sub-targets&#39;&#39;&#39;&#39; which are rocket powered and can be individually launched from the drone when at the proper place and time to provide training for crews firing a missile at the target, and to provide a target for missile quality assurance and lot acceptance testing. The targets are extremely simple and economical, comprising only a symmetrical plastic body with fixed tail surfaces, and a cylindrical rocket motor inside. A removable nose cover initially masks the radar reflector of each target except one until ready for use.

United States Patent Benneche et al.

RADAR-AUGMENTED SUB-TARGET Inventors: Chris Benneche, Newbury Park;

Brochu James W., Granada Hills; Jack S. Conner, Topanga, all of Calif.

Assignee:

Calif.

Filed: Feb. 25, 1974 Appl. No.: 445,153

U.S. Cl. 343/18 B, 273/102 R, 273/l02.2 R Int. Cl. 1-I0lq 15/14 Field ofSearch. 343/18 B; 273/102 R, 102.2 R

References Cited UNITED STATES PATENTS Bishoff et a1. 343/18 B Norman,Jr. 343/188 Northrop Corporation, Los Angeles, I

[451 Feb.11,1975

3,334,345 8/1967 Bradford 343/18 B 3,413,636 11/1968 Migdal ..343/18BPrimary Examiner-T. H. Tubbesing Attorney, Agent, or Firm-William W.Rundle [57] ABSTRACT A remote controlled drone aircraft carryingradaraugmented targets or so-called "sub-targets" which are rocketpowered and can be individually launched from the drone when at theproper place and time to provide training for crews firing a missile atthe target, and to provide a target for missile quality assurance andlot acceptance testing. The targets are extremely simple and economical,comprising only a symmetrical plastic body with fixed tail surfaces, anda cylindrical rocket motor inside. A removable nose cover initiallymasks the radar reflector of each target except one until ready for use.

12 Claims, 9 Drawing Figures I RADAR-AUGMENTIED SUB-TARGET The presentinvention relates to targets and target systems, and more particularly,to an expendable radaraugmented sub-target launched from an airborneremote-controlled drone aircraft, for use in weapon training and missiletesting for example.

Radio-controlled drone targets have been launched from the ground orfrom piloted aircraft for gun or missile testing and gun crew training,these drones being parachute-recovered and salvaged for re-use if notdestroyed by weapon hits or crash landings. Also, targets have beentowed from an aircraft at the end of a long tow cable while missiles arefired at the target. Both these methods are wasteful and unsuitable inseveral respects. Recovery, rebuilding and replacement of the drones isexpensive, while automatic loss of the towed target and its long towcable is also expensive. Further, in the case of the towed target, anangle of attack of the weapon from a head-on direction and up to aprescribed angle away from head-on is prevented due to the positionoccupied by the towing craft.

Thus, it is an object of the present invention to provide a new targetfor the function described which is workable and also economicallyexpendable after a single use, whether intercepted or not.

Another object of this invention is to provide more than one targetcarried by a drone aircraft, together with means causing the firedweapon to track only the desired single target.

A further object is to provide a high speed target simulatingpresent-day high velocity weapons, and a target which will be well awayfrom its launching drone at missile intercept, thus avoiding thenecessity of evasive launching drone maneuvers following target launch.

Briefly, our invention comprises a small, simple rocket type oftargetcarrying radar reflection augmenting means, and support fitting memberson the exterior of the target body for supporting it from a launchingdrone prior to ignition of the target rocket motor. The target ispreferably Wingless but has directional tail fins and preferably hasmeans for spinning itself during its flight after launching. A dronetype target carrier is used, with provisions for carrying at least twosuch targets, provisions for individually launching the targets, meansfor adequately masking the radar augmenting means of each target exceptone, and means for removing the respective masking means at a desiredchosen time.

This invention will be more fully understood from the following detaileddescription of specific apparatus and reference to the accompanyingillustrative drawings.

In the drawings:

FIG. 1 is a perspective view of a drone aircraft showing two wing-tipmounted radar-augmented sub-targets each adapted to be launched and flyfor a predetermined time as a practice target.

FIG. 2 is a front view of the left half of the drone showing details ofthe sub-target mounting.

FIG. 3 is a side inboard profile view of the sub-target.

FIG 4 is a cross-section view of the sub-target, viewed as indicated bybroken line 4-4 in FIG. 3, showing certain longitudinal reflectorstherein.

FIG. 4A is a partial perspective view of the structure of FIG. 4 withthe outer skin removed, showing more clearly the longitudinalreflectors.

FIG. Sis a left side view of the front ofone of the subtargets showing amasking nose cover thereon.

FIG. 6 is a partial cross-sectional view taken as indicated by brokenline 6-6 in FIG. 5, showing details of the removable nose cover.

FIG. 7 is a perspective sketch showing the top shell of the nose cover.

FIG. 8 is a perspective sketch showing the bottom shell of the nosecover.

Referring first to FIG. I for a detailed description of the illustratedexample of the present invention, a drone aircraft 1 having a fuselage2, wing 4, tail surfaces 5 and jet engine inlet 6 carries a sub-target 7at each tip of the wing 4. These are sometimes called subtargets byworkers in the art because aircraft having the same or similarcharacteristics and size of the present drone 1 have normally been usedas targets for missile and gun training. The sub-targets 7 are hereinreferred to as both targets and sub-targets.

As shown in FIGS. 2 and 3, each sub-target 7 carries two slippers 9 onits top side which slide in a rail 10 attached to the underside of thewing 4 and usually extending ahead of and to the rear of the wing 4.Rail 10 may be curved slightly downward or upward to match the chordwisewing contour-or to launch the target 7 in a slight initial downward orupward direction. Such wing-tip mounted arrangement may of course bemodified.

FIG. 3 also shows the internal arrangement of each ofthe targets 7. Inthe nose section II is located a radar reflector 12 such as a Luneberglens for example, supported by lens mounting structure 14 which ispreferably curved to match the rear side: of the lens 12. The centralsection is mostly occupied by an inner body tube 15 shaped to contain aconventional fast burning rocket motor 16 having an electrical ignitorl7, and an exhaust nozzle 19. An outer skin 20 of fiberglass, forexample, covers the target body to the rear of the lens 12, and athree-part metal tail is mounted at the rear. The tail surfaces 18 arepreferably canted slightly as is known in the art to provide spin to thetarget 7 after launch. FIG. 2 shows the trailing edges 21 of the tailcanted slightly to one side of the leading edges. Other spinning meanscan be used if desired, such as canted exhaust nozzles of the rocketmotor 16.

A special unique radar reflective means is provided between the tube 15and the outer skin 20. This comprises circumferential reflectors 24which may be of aluminum acting also as support bulkheads, and a plasticfoam filler 25 contains pairs of longitudinal strip reflectors 26 (seeFIGS. 4 and 4A) mounted at right angles to each other. The reflectors 24and 26 thus act as scintillators during target flight. This radarreflective means does not affect incident electromagnetic energy fromthe front of the target, but when the target is spinning and flyingalone after launching, pulsed radar re flections are caused both by thecircumferential and longitudinal reflectors 24 and 26, especially whenthe incident radiation is at an angle to the target line of flight.

As the controlled drone l is flying with both subtargets 7 retained, thefiring batteries on the ground, for example, can locate and track thedrone I by means of the Luneberg lens 12. Then when the missile orweapon is fired, the ground controller of the drone l is notified andremotely sends a radio signal to ignite the first target motor, and thetarget launches itself at high acceleration from the drone 1. Inoperation, the targettracking radar now tracks only the launched target,since the target has high acceleration (23 g for example) and since amask, to be described next, is fitted over the nose of the unfiredtarget to cover its Luneberglens. The target is usually launched in aslightly upward direction, say at 13 to l7 to the horizon. Assuming anacceleration of about 23 g and a motor burning time of about 1.6seconds, the trajectory of the target is nearly horizontal through itsfirst seconds of flight.

When the two targets 7 are carried by the single drone 1, one of thetargets has a mask 27 in the form of a non-radio-transparent cover overthe target nose, as shown in FIGS. 1 and 5. In this example let us saythe left-hand target is the first to be launched, and therefore the nose11a of the right-hand target has the mask 27 installed.

As further shown in FIGS. 5 through 8, the mask 27 comprises an upperhalf-shell 29 and a lower half-shell 30 molded and assembled in a sizeto be snugly slipped over the target nose and be automaticallyjettisoned upon command. Around the horizontal centerline of thecombined shells, a first collar 31 is bonded to the lower edge of theupper half-shell 29 and a second collar 32 is bonded to the lowerhalf-shell 30 at a position spaced parallel to the upper edge thereof.An encircling pastic foam pad 34 is provided between the edge of thelower half-shell 30 and the collars 31 and 32. Along the midpoint ofthis pad 34 is intermittently laced or otherwise held a pyrofuse wire orpreferably several such wires 35 which are of suitable pyrotechnicmaterial adapted to burn rapidly when ignited. A firing squib 36 withignition leads 37 is positioned at one end of the pyrofuse wires 35 inigniting contact therewith. Preferably, the wires are wound around thesquib 36 and tiedor taped thereto. The squib leads 37 come from a squibfiring circuit 39 which may be in the target 7 but is preferably in thedrone 1 so that it is not expended with the target 7.

Lastly, when the half-shells are joined, a plastic film strip 40 isplaced (without bonding) over the pad 34 and wires 35 on one side, andbonded on the outside only to both the adjacent collars 31 and 32 asshown in FIG. 6, thus holding the nose cover together. The shells may bemade of fiberglass and spray-coated with aluminum 41 on the inside, thusforming the mask 27 when installed over the Luneberg lens reflector 12.The foam pad 34 is flexible and preferably somewhat resilient so thatthe mask 27 will easily stay on the nose during handling and flightuntil jettisoned.

After the first target 7 has been launched and fired upon, the drone 1will continue being flown by the controller until the gun crew havingpractice is ready to fire at another target. The controller then bringsthe drone l to the desired altitude, position and heading for the secondtracking procedure, in the meantime having actuated the squib firingcircuit 39 by remote command radio signal, which is well knownin theart. As the squib 36 is fired, the pyrofuse wires 35 burn or melt apartthe plastic film strip 40, thus separating the shells 29 and 30 andletting them blow or fall away. Now this second target is tracked, andwhen a missile is fired at it, the controller launches the second targetto be followed and hit by the missile. After this, the drone l is flownback to its take-off site and recovered, to be used again by loading twomore targets 7 onto the rails 10.

A conventional type of drone tracking system is usually used to informthe drone controller on the ground.

The tracking signals from the drone I and the remote flight controlsignals to the drone are indicated by the arrow 42 in FIG. 1. Ifdesired, smoke pulses from the drone can be employed to aid in tracking,and in fact smoke producing means can be installed in some targets 7 inthe spaces where the plastic foam 25 is normally placed, if desired.

In the foregoing description, the launching of the target 7 from thedrone 1 has been described as following the instant of missile firing.However, in the case where a close-range target presentation is to bemade, the target 7 may be launched prior to missile firing.

The present targets 7 may of course be made in various sizes and withrocket engines of various thrusts. In an actual example, the target isless than five feet long, weighs about 33 pounds, and has a 2.75 inchrocket motor with a thrust of about 760 pounds, which achieves a maximumspeed of Mach 1.4 at 10,000 feet altitude. A 7-inch Luneberg lens isprovided. Thus it is seen that a very economical realistic target isprovided with the speed and other characteristics as required tosimulate present day weapons and to present a good target for modernmissiles. The targets are abandoned after each flight, but the launchingdrones (also inexpensive) are flown again and again.

The same principles of the present invention would also apply if morethan two sub-targets 7 were desired to be carried by the drone l, theadditional sub-targets being carried at suitable parallel wing stationsor beneath the drone body, or within the drone body. If four sub-targetsare provided, three reflector masks 27 would normally be required, eachhaving a separate and distinct jettison control system.

While in order to comply with the statute, the invention has beendescribed in language more or less specific as to structural features,it is to be understood that the invention is not limited to the specificfeatures shown, but that the means and construction herein disclosedcomprise the preferred form of putting the invention into effect, andthe invention is therefore claimed in any of its forms or modificationswithin the legitimate and valid scope of the appended claims.

What is claimed is:

1. An airborne target for launching from a carrier aircraft comprising:

a. a streamlined body having launching slippers protruding above theupper surface of said body;

b. a tail assembly on the aft end of saidbody;

c. radar reflection augmenting means in the nose of said body;

d. a rocket motor extending along the center of said body with means forigniting said motor at a chosen time to launch said target from saidcarrier aircraft; and

e. additional radar reflective means in said body around said motor,said additional means including a plurality of scintillators.

2. Apparatus in accordance with claim I wherein said motor hassufficient thrust to boost said target to supersonic speed.

3. Apparatus in accordance with claim 1 including means on said targetfor spinning it about its flight axis after launching.

4. Apparatus in accordance with claim I wherein said additionalreflective means comprises lightweight metal circumferential ringsextending from said motor to the outer extent of said body.

5. Apparatus in accordance with claim 1 wherein said additionalreflective means comprises lightweight metal longitudinal strips locatedin the annular space between said motor and the outer extent of saidbody.

6. Apparatus in accordance with claim 1 wherein plastic foam filler isprovided in said body between said motor and the outer extent of saidbody, said foam filling the spaces between said scintillators.

7. Apparatus in accordance with claim 1 including removable nose covermeans surrounding the front and sides of said radar reflectionaugmenting means and forming a radar mask, and remote control meansoperatively connected to said cover means to separate the latter fromsaid target in response to actuation of said remote control means.

8. Apparatus in accordance with claim 7 wherein said nose cover meanscomprises two half-shells, a separable strip normally connecting saidhalf-shells together, and pryrotechnic means ignitable by said remotecontrol means and extending along said separable strip, said pyrotechnicmeans structured to burn through and separate said strip, whereby saidnose cover means is jettisoned 9. Target means comprising:

a. a drone aircraft remotely controlled;

b. a streamlined powered flying target carried near each wing tip ofsaid drone until ready to launch said target;

c. radar reflection augmenting means in each said target; and

d. a rocket motor in each said target being individually ignitableduring drone flight for launching said targets individually from saiddrone.

10. Apparatus in accordance with claim 9 wherein each said target hasadditional radar reflective means therein and means for spinning saidtarget when launched, said additional reflective means producing pulsedreflections as said target spins.

11. Apparatus in accordance with claim 9 including removable nose covermeans forming a radar mask surrounding the front and sides of the radarreflection augmenting means in only one of said targets, andremotecontrol means operatively connected to said cover means toseparate the latter from said one target in response to actuation ofsaid remote control means.

12. Target means comprising:

a. a drone aircraft remotely controlled;

b. a plurality of streamlined powered flying targets carried by saiddrone until ready to be launched;

c; radar reflection augmenting means in each said target;

d. drive motor in each said target being individually startable duringdrone flight for launching said targets individually from said drone;and

e. removable cover means forming a radar mask effectively surroundingthe reflection augmenting means in each of said targets except one, andindividual control means operatively connected respectively to saidcover means to separate the latter from its respective target inresponse to actuation of its said control means.

1. An airborne target for launching from a carrier aircraft comprising:a. a streamlined body having launching slippers protruding above theupper surface of said body; b. a tail assembly on the aft end of saidbody; c. radar reflection augmenting means in the nose of said body; d.a rocket motor extending along the center of said body with means forigniting said motor at a chosen time to launch said target from saidcarrier aircraft; and e. additional radar reflective means in said bodyaround said motor, said additional means including a plurality ofscintillators.
 2. Apparatus in accordance with claim 1 wherein saidmotor has sufficient thrust to boost said target to supersonic speed. 3.Apparatus in accordance with claim 1 including means on said target forspinning it about its flight axis after launching.
 4. Apparatus inaccordance with claim 1 wherein said additional reflective meanscomprises lightweight metal circumferential rings extending from saidmotor to the outer extent of said body.
 5. Apparatus in accordance withclaim 1 wherein said additional reflective means comprises lightweightmetal longitudinal strips located in the annular space between saidmotor and the outer extent of said body.
 6. Apparatus in accordance withclaim 1 wherein plastic foam filler is provided in said body betweensaid motor and the outer extent of said body, said foam filling thespaces between said scintillators.
 7. Apparatus in accordance with claim1 including removable nose cover means surrounding the front and sidesof said radar reflection augmenting means and forming a radar mask, andremote control means operatively connected to said cover means toseparate the latter from said target in response to actuation of saidremote control means.
 8. Apparatus in accordance with claim 7 whereinsaid nose cover means comprises two half-shells, a separable stripnormally connecting said half-shells together, and pryrotechnic meansignitable by said remote control means and extending alonG saidseparable strip, said pyrotechnic means structured to burn through andseparate said strip, whereby said nose cover means is jettisoned 9.Target means comprising: a. a drone aircraft remotely controlled; b. astreamlined powered flying target carried near each wing tip of saiddrone until ready to launch said target; c. radar reflection augmentingmeans in each said target; and d. a rocket motor in each said targetbeing individually ignitable during drone flight for launching saidtargets individually from said drone.
 10. Apparatus in accordance withclaim 9 wherein each said target has additional radar reflective meanstherein and means for spinning said target when launched, saidadditional reflective means producing pulsed reflections as said targetspins.
 11. Apparatus in accordance with claim 9 including removable nosecover means forming a radar mask surrounding the front and sides of theradar reflection augmenting means in only one of said targets, andremote control means operatively connected to said cover means toseparate the latter from said one target in response to actuation ofsaid remote control means.
 12. Target means comprising: a. a droneaircraft remotely controlled; b. a plurality of streamlined poweredflying targets carried by said drone until ready to be launched; c.radar reflection augmenting means in each said target; d. drive motor ineach said target being individually startable during drone flight forlaunching said targets individually from said drone; and e. removablecover means forming a radar mask effectively surrounding the reflectionaugmenting means in each of said targets except one, and individualcontrol means operatively connected respectively to said cover means toseparate the latter from its respective target in response to actuationof its said control means.